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    耐蚀合金临界点蚀温度标准试验方法比较

    Comparison of Standard Methods for Critical Pitting Temperature Testing of Anticorrosion Alloys

    • 摘要: 对失重法、恒电位法和动电位法三种标准临界点蚀温度(CPT)测定方法进行了对比,分析三种试验方法的特点及适应性,着重研究了不同试验环境和方法对S22053双相不锈钢CPT测定的影响。结果表明:由于试验条件及判定发生点蚀的临界条件有所不同,三种测试方法测得的S22053双相不锈钢的CPT不同,分别为35.6,53.1,55.0℃。失重法采用的试验环境最苛刻,测得的CPT远低于恒电位法和动电位法测得的,且测试时间长,对于单一材料的点蚀形成过程不能准确地描述,但对设备要求低,且操作简单;动电位法和恒电位法对设备要求高,尤其是恒电位法,其升温速率和溶液中的温度梯度对试验结果均存在影响,但二者的测量参数都可较准确地反映材料形成稳态点蚀的临界条件;且恒电位法还具有试样数量少、测试时间短及测得的CPT为一个具体的数值等优点。

       

      Abstract: Three standard methods for critical pitting temperature (CPT) testing, weight loss method, potentiostatic method and potentiodynamic method, were compared to study their characteristics and adaptability. The effects of different test environments and methods on CPT determination of S22053 duplex stainless steel were emphatically studied. The results show that CPT values tested by three methods for S22053 duplex stainless steel were different, which were 35.6, 53.1, and 55℃, respectively, because of different experimental conditions and critical conditions for determining pitting corrosion. Due to the harsh test environment used in the weight loss method, the CPT measured by the weight loss method was much lower than that measured by the potentiostatic method and the potentiodynamic method. The weight loss method needs a long test time and can not accurately describe the pitting formation process for a single material, but has low equipment requirements and is easy to operate. The potentiodynamic method and potentiostatic method have high requirements for equipment, especially the potentiostatic method. The heating rate and the temperature gradient in the solution have an effect on the test results, but the measurement parameters both in the potentiodynamic method and in the potentiostatic method can accurately reflect the critical conditions for the formation of steady-state pitting corrosion. The potentiostatic method also has the advantages of less sample number, short test time and measured CPT as a specific value.

       

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